Events & Promotions
| Last visit was: 06 Sep 2026, 11:13 |
It is currently 06 Sep 2026, 11:13 |
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Sep 0712:01 AM PDT
-11:59 PM PDT
On the 7th, GMAT Club Tests will be Free! Including all the Quizzes, Questions, and Tests. 12 AM - 11:59 PM PDT- Sep 07
10:00 AM PDT
-11:00 AM PDT
A complete walkthrough of GMAT Club’s free 12-week GMAT study plan: what you study each week, how progress and goals are tracked, how the error log works, and how your practice unlocks paid tools at no cost. 
Sep 0201:00 PM EDT
-11:59 PM EDT
Take 30% off all study plans with code COURSEWORK - Expires on Monday 9/7
Sep 0410:00 AM EDT
-11:59 PM EDT
We’ve worked incredibly hard to build TTP into the best test prep experience possible, and it would mean a lot to us to win Newsweek’s 2026 Readers’ Choice Award for Best Test Prep. If TTP has helped you, we’d be incredibly grateful for your vote.
Sep 0609:30 AM EDT
-12:30 PM EST
Top scores are possible when you enroll in a powerful EA course, taught live online + 6 months access to TTP OnDemand video courses included! Perfect class schedule and easy course access for working professionals. Class starts Sundays Sept. 6, 2026.- Sep 09
07:00 AM PDT
-10:00 AM PDT
Meet AdComs and explore top Master’s programs - MiM, MiF, MSc, MSBA and more. - Application Fee Waivers - Free 1-Week of GMAT Club Tests: - Master's Application Toolkit - Grand Prize Giveaway - Sep 09
10:00 AM PDT
-11:00 AM PDT
Three MBA applications. Three rejections. No interview invites. A year later, Aman was admitted to Cambridge Judge, SMU, and IMD. In this episode of MBA Admit Stories, Aman shares how he rebuilt his MBA application... 
Sep 1507:00 PM EDT
-09:00 PM EST
Elite scores are possible when you enroll in a powerful GMAT course, taught live online + 6 months access to TTP OnDemand video courses included! Class starts Tues/Thurs Sept. 15, 2026 - Nov. 15, 2027, 7:00pm-9:00pm EST
Sep 2108:00 PM EDT
-10:00 PM EDT
Boost your GMAT score in less than one month in a live online class + 6 months access to TTP OnDemand video courses included! Class starts Mon, Tues, Wed, Thur, Fri Sept. 21, 2026 - Oct. 9, 2027, 7:00pm-10:00pm EST
19 Apr 2016, 11:03
Kudos
Bookmarks
shivakumarmakka
Dear shivakumarmakka
I'm happy to respond.
Let's say
A = black earthworm population
B = red-brown earthworm population
Before event, A < B. Technically, A = 5B, approximately.
BUT, be careful. After event, it does not say A > B or even A = B. The exact wording is
"The population of black earthworms is now almost equal to that of the red-brown earthworm ..."
Technically, A is still less than B: now, not five times less, but just slightly less. It's misreading the question to say that A is greater than B.
Also, notice that nowhere in the question itself does it suggest that the black worms have increased. The prompt argument doesn't even contain the word "increase." In fact, the question is about B decreasing. The factory has blackened the woods, and presumably the black worms are now well camouflaged, but the red-brown worms are easier to spot, so the birds snack on these. We don't know whether the black worms have stayed the same or increases, but through some combination of B dropping and A staying the same or rising, A has almost caught up to B.
My friend, you have to remember that GMAT CR is as precise as mathematics. You have to look at every single word incredibly carefully. It appears you got the gist of the argument and concluded in your own mind that it was saying things different from what it actually says. Be very careful. As in any argument in the business world, the fine print matters, and many business deals that look great on the surface turn out to be nightmares when you examine the details.
Does all this make sense?
Mike
22 Oct 2018, 14:56
Kudos
Bookmarks
TGC
okay here is my reasoning why i chose C
Since, in 1990, a factory was built in Millerton and emissions from the factory blackened much of the woods.
The population of black earthworms is now almost equal to that of the red-brown earthworm, i.e. the population of black worms increased and the population of brown worms stagnated
Local ecologists say it is the blackening of the woods.
Ecologists`s claim implies that emissions enabled black worms to use their color as a comouflage.
To strengthen this claim one need to find a factor that could have negative affect on black worms. so based on option (C) despite favourble conditions for the red brown worm, its population didn`t grow whereas for black worm though climate conditions were less favourable, their black camouflage gave them opprtunity for survival and growth in black woods. hence C
Climate conditions since 1990 have been more favorable to the survival of the red-brown worm than to the black worm.
14 May 2019, 09:42
Kudos
Bookmarks
A and B are good answers, but C is better.
A strengthens the argument because it says the red worm population is falling. One possible explanation is the black worms are now better camouflaged so the birds are eating more red worms.
But A isn’t ideal because there are other plausible explanations. Maybe there is a disease that’s killing red worms. We don’t know. A is tempting us to assume that the blackening of the forest is why the red worm population is falling but we don’t really know that for sure. So maybe this fact strengthens, or maybe it’s just a coincidence.
B is good, too, but it isn’t perfect. It says birds prefer black worms so you you would expect them to eat more black worms. Yet, the black worm population is rising. So we’re tempted to assume the birds would rather eat black worms but they aren’t doing so because the black worms aren’t visible so the birds settle for eating red. Okay, maybe. Or maybe the birds are still eating tons of black worms. We know the population of red and black is now equal but we don’t know that there are more black worms. Maybe they’re equal entirely because the population of red worms fell. Is that because the birds can see the red worms and are eating more of them? That’s a fair supposition but maybe something else, like disease or climate change, is causing the red worm population to fall.
And that takes us to C. C is best because it is ruling out these alternative explanations. A and B are plausible explanations, but they leave other possibilities open. C forecloses those possibilities.
This one is really hard, I would not fault anyone for picking A or B. We see a lot of questions where all the answers are bad and we have to find the least bad. Here, we have to pick the best of three pretty good answers.
Posted from my mobile device
A strengthens the argument because it says the red worm population is falling. One possible explanation is the black worms are now better camouflaged so the birds are eating more red worms.
But A isn’t ideal because there are other plausible explanations. Maybe there is a disease that’s killing red worms. We don’t know. A is tempting us to assume that the blackening of the forest is why the red worm population is falling but we don’t really know that for sure. So maybe this fact strengthens, or maybe it’s just a coincidence.
B is good, too, but it isn’t perfect. It says birds prefer black worms so you you would expect them to eat more black worms. Yet, the black worm population is rising. So we’re tempted to assume the birds would rather eat black worms but they aren’t doing so because the black worms aren’t visible so the birds settle for eating red. Okay, maybe. Or maybe the birds are still eating tons of black worms. We know the population of red and black is now equal but we don’t know that there are more black worms. Maybe they’re equal entirely because the population of red worms fell. Is that because the birds can see the red worms and are eating more of them? That’s a fair supposition but maybe something else, like disease or climate change, is causing the red worm population to fall.
And that takes us to C. C is best because it is ruling out these alternative explanations. A and B are plausible explanations, but they leave other possibilities open. C forecloses those possibilities.
This one is really hard, I would not fault anyone for picking A or B. We see a lot of questions where all the answers are bad and we have to find the least bad. Here, we have to pick the best of three pretty good answers.
Posted from my mobile device
PriyankaPalit7
Joined: 28 May 2018
Last visit: 13 Jan 2020
Posts: 116
Own Kudos:
Given Kudos: 883
Location: India
Schools: ISB '21 (A)
GMAT 1: 640 Q45 V35
GMAT 2: 670 Q45 V37
GMAT 3: 730 Q50 V40
05 Jun 2019, 21:32
Kudos
Bookmarks
I chose B as my answer because of the following reasoning.
To strengthen an argument that A causes B, we should remove any possibility of C causing B.
A = Forest turning back
B = Black earthworm population increasing
C = The birds DO NOT prefer black earthworms over red earthworms
So, when we remove another possible factor (C) that could cause (B), it strengthens the argument .
The population of black earthworms have increased significantly NOT because the birds DO NOT prefer black earthworms.
OR
The population of black earthworms have increased significantly even though the birds prefer to eat black earthworms.
If the birds do not prefer black earthworms, then, now that the forest has turned black, red earthworms have lost their camouflage, so birds are eating more red earthworms. The population of red earthworms has decreased and so the number or black earthworms is almost equal to the number of red earthworms now.
Basically, the equality of the number of black and red earthworms is not because birds are eating red earthworms more, but because black earthworms are getting camouflage now that the forest has turned black.
So, I feel statement B also strengthens the argument.
Can anyone please explain why this reasoning is wrong? Is it too far fetched?
To strengthen an argument that A causes B, we should remove any possibility of C causing B.
A = Forest turning back
B = Black earthworm population increasing
C = The birds DO NOT prefer black earthworms over red earthworms
So, when we remove another possible factor (C) that could cause (B), it strengthens the argument .
The population of black earthworms have increased significantly NOT because the birds DO NOT prefer black earthworms.
OR
The population of black earthworms have increased significantly even though the birds prefer to eat black earthworms.
If the birds do not prefer black earthworms, then, now that the forest has turned black, red earthworms have lost their camouflage, so birds are eating more red earthworms. The population of red earthworms has decreased and so the number or black earthworms is almost equal to the number of red earthworms now.
Basically, the equality of the number of black and red earthworms is not because birds are eating red earthworms more, but because black earthworms are getting camouflage now that the forest has turned black.
So, I feel statement B also strengthens the argument.
Can anyone please explain why this reasoning is wrong? Is it too far fetched?
